
Built by Swan Hunter & Wigham Richardson, Laconia was launched on 27 July 1911 and delivered to the Cunard Line on 12 December 1911. She began service on 20 January 1912 and was the first Cunard ship to bear that name.
On the outbreak of World War I Laconia was converted into an armed merchant cruiser and based at Simon's Town, South Africa in the South Atlantic, from which she patrolled the South Atlantic and Indian Ocean until April 1915.
She was then used as a headquarters ship for the operations to capture Tanga and the colony of German East Africa. Four months later Laconia returned to the patrolling of the South Atlantic. She was handed back to Cunard in July 1916 and on 9 September resumed service.
On 25 February 1917 she was torpedoed by the German U-50 six miles (11 km) northwest by west of Fastnet while returning from the United States to England with 75 passengers (34 first class and 41 second class) and a crew of 217 under the command of Captain Irvine.
The first torpedo struck the liner on the starboard side just abaft the engine room, but did not sink her. Twenty minutes later a second torpedo struck the engine room, again on the starboard side. The vessel sank at 10:20 pm. Twelve people were killed, six crew and six passengers.